DE2435553C2 - Optical flint glasses with temperature-independent optical path length in the range n deep e 1.58-1.66, V deep e 44-30 based on alkali-alkaline earth borosilicate fluoride + TiO deep 2 + ZrO deep 2 + Nb deep 2 O deep 5 - Google Patents

Description

the sum of the SiO ₂ - B ₂ O ₃ and the P ₂ O ₅ 33 tv s 45 percent by weight, the sum of ZrO ₂ + TiO ₂ 12 to 27 percent by weight and, in addition to the oxides mentioned, up to 7 percent by weight ZnO, up to 5 Percent by weight of CdO, PbO and / or up to 5 percent by weight of 3-valent oxides, such as La ₂ O ₃ , Al ₂ O ₃ , Y ₂ C) ₃ , Sb ₂ O ₃ , Bi ₂ O ₃ and WO ₃ , for setting a desired optical position and can be used to _{stabilize crystallization without exceeding the value Gelabs)} · 10 ⁶ / ° C = 2.5 and the expansion coefficient η ^{· 10 7} / ° C in the temperature range from -30 to +70 ⁰ C above 120 increases.

2. Optical flint glass according to claim I !, characterized in that the glass consists of:

SiO ₂ 16.3 percent by weight

B ₂ O ₃ 25.8 weight percent

K ₂ O 20.6 percent by weight

BaO 9.8 percent by weight

ZrO ₂ 14.0 percent by weight

TiO ₂ 8.8 weight percent

Nb ₂ O ₅ 4.7 weight percent

F 12.0 percent by weight

and that it has the following properties:

H, 1.5884

v _t 39.90

Specific weight s 2.895

«· H) ⁷ Z ⁰ C 133

-30 to +70 ³ C

7g C 392 -

& - 10 ⁶ C -6.6

CUm-IOTC O

Ε module [kp / mm ² ] 5343 "

F'oiss. Number .269 "

3. Optical flint glass according to claim il, characterized in that the glass consists of:

SiO ₂ 16.3 weight percent ^

B ₂ O ₃ 25.8 weight percent

K ₂ O 20.6 percent by weight

BaO 9.8 percent by weight

ZrO ₂ 4.0 percent by weight

TiO ₂ 8.8 weight percent

Nb ₂ O ₅ 14.7 weight percent

F 12.0 percent by weight

and that it has the following properties:

553 ₂ I.

., 1.61450

,! ■ '36.31

, / ■ lore ι ' ⁰ - ⁷

-30 to +70 ⁰ C

Tg ⁰ C 448

iik- .10V ⁰ C -6.7

GT ^ -Kfrc +0.1

£ module [kp / mm ² ] 5708

4. Optical flint glass according to claim I, characterized in that ~ the glass consists of:

16.3 percent by weight 25.8 percent by weight 20.6 percent by weight '4.8 percent by weight

ZrO ₂ 9.0 percent by weight

JjO ₂ 8.8 percent by weight

Nb ₁ O ₅ 4.7 weight percent

ρ. "12.0 percent by weight

and that it has the following properties:

11, 1.61527

_r 39.85

• lOYC 100-2

-30 to +70 ⁰ C

Tg ^c C 434

- ^ - · 10 ⁶ Z ⁰ C -4.2

"l +2.0

5. Optical flint glass according to claim 1, characterized in that the glass consists of:

SiO ₂ 12.3 percent by weight

B ₂ O, 29.8 weight percent

KO 20.6 percent by weight

BaO 19.8 percent by weight

ZrO ₂ 4.0 percent by weight

JjO ₂ 8.8 percent by weight

Nb ₂ O ₅ 4.7 weight percent

F 5.0 percent by weight

and that it has the following properties:

"1.60635

rj 42.60

•! ⁰⁷ / "C 103.3

-30 to +70 ⁰ C

^ - • lorc -5

G., 'L-10 ⁶ / ° C +1.2

It is known that wall fronts are deformed in a glass when the optical path lengths are of different sizes due to temperature gradients occurring at different points on the glass.

Optical instruments, e.g. B. in space vehicles, are through intermittent solar radiation and through radiation into space, moreover emitted and / or reflected IR radiation from nearby planets exposed to strong temperature differences.

These temperature differences can cause wave deformations in the optical glasses (} he resolving power of optical systems is considerable Reduce.

They can also do aerial photography there occurring temperature gradients to disturbing wave deformations to lead.

Ps is therefore of great interest in optical fS ih G

This contrast shows the difficulties involved in the Development of glasses with temperature-independent optical path length occur.

It has been found that the athermal wave aberration is not only determined by G, but that the refractive index gradient resulting from the thermal stress a _{w also} determines the wave aberration. / ~ - Sn "da ..,,.".,,.

^GroIie Γα " dt ^he 8 ^grows > ^{so people:} Athermali-

SyftemSi and optical closure windows made of Glä- Γα dt

sern can be achieved with temperature-independent optical path. This value can be small

^{Halves become} ' ^if «· ^£ - ^{module and} £ of ^{the glass}

^{small 3Ind} · ^Im a ^ mernen .st - ^ ■ _w positive, so

that because of the compensation, the "classic G-value" should be negative. The requirement for the »classic G value «is then zero or negative.

So far there are no flint glasses in »optical Tepid area

| S plane-parallel closing windows or plane «ii" illelen Laser rods are the result of temperature restraint resulting change in optical path length

I w = W ₁ -W ₂ = d U (n - 1) + --I It,

where d = thickness of the glass,
, 1 = refractive index,
"= Thermal expansion,
I = temperature.

_An "fco * Wdl-ddb" *, is effected, """ _r 1.58 to 1.67, v _e 44 to 30

known that meet these conditions. Ateabe of the present invention is .ts, access

an vers n ^ iVtiimo 7 « _nt H" a a *

divorced is great. The equation shows that dm op-

The temperature difference \ W can be reduced by reducing the thickness d of the glass element, the temperature difference Ii or the size

G: = (n - 1) u + ~ _t . The size G only depends on the physical properties of the glass and should be as small as possible, ideally G.

Dii * size of the A -value is of two overlapping Components dependent:

1. The volume expansion of the glass resulting from the rising temperature causes a Change according to small refractive indices, d. H.

you ,,,
a negative J ₁ value.

2. The UV natural frequency. Z _{0 of} the glass is shifted to a greater wavelength with increasing temperature and thereby the refractive index

increased (== positive _J; valuej.

For most glasses, the under 2 prevails

called influence, d. i.e., the "" values are positive.

To get negative ^ "values, you have to enter the Glass such components are introduced which

a) the temperature dependence of the UV natural frequency is as small as possible and / or

b) a shift of the UV natural frequency / <, to ^ bring about small wavelengths.

Nachl the thermal expansion is "impli7.it included in the value ψ, and it results in the requirement of a high thermal expansion. To

With the order of l G = (n - 1) ■ u + -gy- = 0, on the other hand, a value as small as possible must be aimed for.

educational qualifications are excluded.

_D i _e ses erfindungsaernäß object is achieved with ^{glasses 'd' e} ^ are sammengesetzt of the following components in weight percent.

SiO, 6 to 25

^ q ¹ 13 to 23

ZrO ₂ 4 to 17

TiO ₂ x 6 to 10

Nb, O, 4 to 20

P ₂ O ₅ 0 to 12

F 6 to 12

the sum of the SiO ₂ - B ₂ O ₃ and the P ₂ O _{5 being 38 to 45} percent by weight, the sum of ZrO, + TiO _{2 being} 12 to 27 percent by weight and, in addition to the oxides mentioned, up to 7 percent by weight of ZnO. up to 5 percent by weight of CdO, PbO and / or up to 5 percent by weight of trivalent oxides, _wje ^^ _{Α ,? ο} ^ γ ^ ^^ ^ O ₃ and WO ₃ ,

can wcrden used for setting a desired optical layer _{and? m} i _{Cristal isati} onsstabilisierung without the value

_ubersc is -juen h, and the coefficient of expansion <· 10 "'/ C in the temperature range of -. 30 to 4-7O ⁰ C over 120 increases.

_{Mi (dcn} f _{o] "cn} d _cn invention together-settlement glasses are obtained, the G ₁ ,,,,,,., ■ 10" reach value = 0,. It was found that the other effects of boric acid and des Huors ^ _(Jjc Ej _uen f _rC q _Ucn z von / _{fl are} best preserved. i.e. "h .. that the athermal properties are not adversely changed if _Zr o, - TiO ₂ - Nb ₂ O ₅ in the as shown in the following examples:

24

For example

SiO ₂ 16.3 percent by weight

B ₂ O ₃ 25.8 weight percent

, K ₂ O 20.6 percent by weight

BaO 9.8 percent by weight

ZtO ₂ ■ 14.0 percent by weight

Ti 88 Gi

TiO ₂

Nb ₂ O ₅

e _e

Specific weight s

«· 10 ⁷ / ° C ... 113

-30 to +70 ⁰ C

Tg ⁰ C 392

8.8 percent by weight

4.7 weight percent 12.0 weight percent

1.5884 39.90

2,895

G _{e {abs)} ■ 10 ⁶ Z ⁰ C

£ module [kp / mm ² ]
Poiss. number

-6.6

5343
0.269

A partial exchange of ZrO ₂ by Nb ₂ O ₅ for setting even lower v _e values is possible. Without increasing the G _e value, like the following

Example 2 shows:. .

Example2

SiO ₂ 16.3 percent by weight

B ₂ O ₃ 25.8 weight percent

K ₂ O 20.6 percent by weight

BaO 9.8 percent by weight

ZrO ₂ 4.0 percent by weight

TiO ₂ 8.8 weight percent

Nb ₂ O ₅ 14.7 weight percent

F 12.0 percent by weight

n _e 1.61450

r _e 36.31

s 2.88

<ilO ⁷ / ° C 110.7

-30 to +70 ⁰ C

Tg ⁰ C 448

Ε module [kp / mm ² ]

-6.7

0.1 5708

If Nb ₂ O _{5 is} replaced by BaO • unexpectedly, the G _e value increases considerably with a decreasing expansion coefficient:

Example 3

SiO ₂ 16.3 percent by weight

B ₂ O ₂ 25.8 weight percent

K ₂ O 20.6 percent by weight

BaO 14.8 percent by weight

ZrO ₂ 9.0 percent by weight

TiO ₂ 8.8 weight percent

Nb ₂ O ₅ 4.7 weight percent

F 12.0 percent by weight

1627

n _e 1.61527

v _e 39.85

s 2.983

«• 10 ⁷ / ° C 100.2

-30 to +70 ⁰ C

7g ° C

_{c (abs)}

lore

434

-4.2 +2.0

The use of Na ₂ O or Li ₂ O instead of K ₂ O is possible in small amounts <2%, but in larger amounts it is unfavorable because the expansion coefficient is increased very much. The easier evaporation of the alkali components with fluorine has a disadvantageous effect on industrial production by selective surface evaporation with regard to homogeneity.

With increasing BaO content and decreasing In the fluorine content, the coefficient of expansion becomes smaller, the refraction of light increases and accordingly the G ^ value increases to + 1.2, as example 4 shows:

Example 4

SiO ₂ 12.3 percent by weight

B ₂ O ₃ 29.8 weight percent

K ₂ O 20.6 percent by weight

BaO 19.8 percent by weight

ZrO,
TiO ₂
Nb ₂ O ₅
F.

-30 to + 70'C

4.0 percent by weight 8.8 percent by weight 4.7 percent by weight 5.0 percent by weight 1.60635 42.60 10 \ 3

+1.2

The sum of the components

BaO + ZrO ₂ + TiO _: + Nb ₂ O ₅

is 32 to 45 percent by weight, the fluorine content W being 5.0 percent by weight. Up to 20 percent by weight of BaO can be replaced by SrO and up to 5 percent by weight by MgO, whereby it must be ensured that the K ₂ O content must not be less than 13% so that the G _e value of + 2.5 · 10 " ⁶ C is not exceeded. By further exchanging SiO ₂ for B ₂ O ₃ and incorporating Al ₂ O _3, G ₁ values <O can be achieved, see Examples 5 and 6, but the tendency to crystallize is then increased strong that no larger objective disks (300 mm , 0.60 mm thick) can be produced. Crystallization-stable compositions achieve G _c values between 0.5 and 1.2 · 10 ^-6 / ° C. (see Examples 4 and 7). The chemical resistance of the glasses decreases with increasing BaO content. The compositions with BaO contents 5 to 20 percent by weight are particularly favorable.

The invention is illustrated by the following

games explained in more detail:

Example 5

SiO ₂ 8.0 weight percent

B ₂ O ₃ 34.1 weight percent

K ₂ O 20.6 percent by weight

BaO 9.8 percent by weight

TiO ₂ 8.8 weight percent

ZrO ₂ 4.0 percent by weight

Nb ₂ O ₅ 14.7 weight percent

F 12.0 percent by weight

n _e 1.61525

previous year 34.88

«• 10 ⁷ / ^c C 116.1

-30 to +70 "C

-8.1 -0.9

Example 6

SiO ₂ 16.3 percent by weight

BJO ₃ 25.9 percent by weight

K ₂ O 20.7 weight percent

BaO 9.8 percent by weight

Al ₂ O ₃ 4.5 percent by weight

TiO ₂ 8.8 weight percent

ZrO ₂ 4.0 percent by weight

Nb ₂ O ₅ 10.0 weight percent

(+ F 12.0 percent by weight)

H ₁ , 1.58746

previous year 37.11

a -10 ⁷ Z ⁰ C 116.2

. -30 to +70 ⁰ C
you.

^J e (abs)

ίο ^6/0 c ■

10 ⁶ Z ⁰ C

-7.6 -0.7

Example 7

SiO ₂ 16.3 percent by weight

B ₂ O ₃ 25.7 weight percent

K ₂ O 20.7 weight percent

BaO 14.8 percent by weight

TiO ₂ 8.8 weight percent

ZrO ₂ 4.0 percent by weight

Nb, O ₅ 9.7 percent by weight

(F Γ 12.0 percent by weight)

1.60384 39.42 109.3

η?

^l' e

α-10 ⁷ Z ° C

-30 to + 7O ⁰ C

¥ * ■ -10 ⁶ / ° C -6.1

^G c «.bs)" 1O ⁶ Z ⁰ C +0.5

£ module [kpZmm ² ] 5989 Poiss. Number 0.267

The compositions of the glasses according to the invention are in the following range:

Nb ₂ O ₅

Weight percent

D to 25

15 to 36

O to 12

13 to 21

6 to 30

4 to 17

6 to 10

4 to 20

5 to 12

ZnO Obis 7

PbO Obis 5

Al ₂ O ₃ Obis 5

La ₂ O ₃ Obis 5

Bi ₂ O ₃ Obis 5

Sb ₂ O ₃ Obis 5

WHERE ₃ Obis 5

Y ₂ O ₃ O to 10

Ta ₂ O ₅ O to 10

where ZnO, PbO, Al ₂ O ₃ , La ₂ O ₃ , Bi ₂ O ₃ , Y ₂ O ₃ (Gd ₂ O ₃ ), Sb ₂ O ₃ , Ta ₂ O ₅ , WO ₃ for setting a

desired optical position and can serve for crystallization stabilization without the

^J elahs)

10 ⁶ Z ⁰ C value becomes> 2.5.

BaO can be replaced by up to 15% by SrO, up to 8% by CaO, up to 5% by MgO, Nb ₂ O ₅ up to 10% by weight by Ta ₂ O ₅ , if it is expedient for crystallization stabilization .

The fluorine components of the compositions mentioned generally act adequately as refining agents. However, it is not ruled out that As ₂ O ₃ and Sb ₂ O ₁ can optionally be used as additional refining agents. The fluorine replaces the corresponding proportions of oxygen and is bound to potassium as potassium fluoride or potassium bifluoride. However, fluorine can also be _{bound to barium as BaF 2} or other cations mentioned.

The use of Li ₂ O and Na ₂ O in small amounts offers no particular advantages, except that the coefficient of expansion, as is to be expected, increases.

The glasses according to the invention from this composition range meet, in addition to those already mentioned, the following conditions:

The expansion coefficient

10 ⁷ Z ° C
! JO to +70 "C

less than 120.

The glasses with a G _{r (eAs)} · Kf " 'C value> 0.5 are characterized by a particularly high crystallization stability, which enables the technical production of large-piece optics (minimum dimensions of 300 mm 0, thickness 60 mm).

The glasses according to the invention have good chemical resistance because of the high proportions of TiO _{2 - / UrO 2} - Nb ₂ O _5.

The glasses according to the invention have positive "relative partial dispersion" * - - ^f = PgF in comparison

n _f - n _c

to conventional flint glasses with a similar or identical optical position (Table 3).

In Table 1, the mentioned and other to composition examples, in Table 2 the corresponding physical properties together summarizes shown.

Melt example for a 6-1 melt:

n.

1.60635
42.60
103.3

• 10 ^7o C

-30 to +70 ⁰ C

Ge ₁₀ W-IO ⁶ Z ⁰ C +1.23

composition

Oxides

(Weight percent)

Initial weight
raw materials

(kg)

SiO ₂ B ₂ O ₃
BaO
BaO
K ₂ OK ₂ O TiO ₂ ZrO ₂ Nb ₂ O ₅

12.31

29.88

5 _: 76

14.00

14.36

6.20

8.84

3.98

4.67

5.00

SiO ₂

H ₂ BO =,

Ba (NOj) ₂

BaCO ;,

KNO ₃

KHF ₂

TiO ₂

ZrO ₂

Nb ₂ O.,

4.932
21,153
3.94 «
7.164
8,447
4.126
3,552
1.603
1,871

The well-mixed mixture is refined at 1160 to 1220 ° C for about 8 hours in a Pt crucible a 2 hour at 1280 ^c C and 1 hour at HOO ⁰ C, run 1V ₂ hours from 1100 to 92o ⁰ C abgerühi in molds preheated left .

The glass blocks are from 450 ° C depending on the request 6'C / hour. or cooled down more slowly.

Table I.

Al ₂ O ₃ La ₂ O ₃

16.3 25.8

20.6 9.8

16.3 25.8

20.6 9.8

16.3 25.8

20.6 14.8

12.3 29.8

20.6 19.8

16.3
25. ¹ y

20.7
9.8

16.3

25.7

20.7
14.8

4.5 -

6.3
35.8

20.6
9.8

9.3

32.8

20.6
14.8

Ta ₂ O ₅ Nb ₂ O ₅

14.0

4.7 12.0

4.0

14.7 12.0

9.0 8.8

4.7 12.0

4.0 8.8

4.7 5.0

4.0
8.8

10.0
12.0

4.0

9.7
12.0

14.0

4.7
12.0

4.0
8.8

9.7
6.0

(Continuation)

SiO ₂ B ₂ O ₃

table

Il

16.3 25.9

K ₂ O 7/20

BaO 9.8

ZnO -

PbO -

Al ₂ O ₃ La ₂ O ₃ -

Y ₂ O ₃ -

Ta ₂ O ₅ Nb ₂ O ₅

4.0 8.8 4.5 10.0 12.0

Physical Properties

12th

16.3 25.8

14.6 25.7

4.0 8.8

4.8 12.0

13th

16.3 25.8

20.6

6.0 4.0 8.8

9.7 12.0

14th

16.2

25.7

14.2 16.0

4.4 8.8

14.7 12.0

16.3

25.7

20.7

7.3

16.5
8.8

4.7
12.0

1.58842 1.61450 1.61527 39.7 35.7 39.9

2.845 2.882 2.983 16

15.2
24.2

! 9.3
9.2
6.8

4.0
8.2

13.7
IZO

17th

16.3
25.9

16.6
14.8

4.0
8.8

9.6
12.0

18th

23.0
18.6

20.4
20.6

4.0
8.8

4.6
12.0

16.3 15.0 10.8 20.6 9.8

4.0 - -

1.60381 1.61525 1.58746 1.60384 1.59657. 1.61: 43.0 34.9 37.1 39.4 38.3 39.4

2.962 2.839 2.779 2.942 Z810 2.87 '

11th

continuation

Physical Properties

η- ΙΟ ⁷ / C

-IO to +70 "C

Tg C

113.3

392

-6.6

± 0

110.7

399 -6.7 + 0.1

100.2

434
-4.2
+ 2.0

(Continuation)

Physical
properties

12th

13th

104.4

443 -5.3 + 1.0

110.0 116.2 109.3 118.2 108.4

375 381 421 389 428

-7.4 -7.6 -6.1 -7.5 -5.5

-0.7 -0.7 +0.5 -0.5 +1.2

16

Ig

19th

H ₁ .
v _e

10 "/ ⁰ C

1.61657 1.60773 1.60877 1.6) 376 1.65105 1.60720 1.63323 1.61129 1.59532 1.6359:

38.9

2.926

105.5

«· 10 ⁷ Z ⁰ C

-10 to +70 ⁰ C

Tg ^r C 437

-4.8

+ 1.7

38.0

2.916

110.9

406 -5.8 + 0.9

42.4 3.13 101.6

438 -5.1 + 1.1

39.3

2,898

102.4

442
-4.1

+ Z2

34.5

3.059

92.1

444

-3.5 + 2.5

2.862

103.9

416
-4.9
+ 1.4

36.4

3.002

99.9

421
-3.2
+ 2.5

38.6

3.002

109.2

413

-5.8

+0.9

Table 3

Type (example) "j

PgF

p- .αν c

F5
F8

TiF 5

LF 2
LF 5

F8

(15)

(2)

(D

(7)

BaSF 3

(3)

1.603420 38.03 0.5790 + 3.3 + 8.1 1.595510 39.18 0.5772 + 3.3 + 8.2 1.60182 38.65 0.5868 -4.9 + 1.4 1.59355 35.51 0.5928 -1.2 +4.2 1.60809 36.41 0.5936 -6.7 +0.1 1.58921 40.94 0.5746 +0.9 + 6.2 1.581440 40.85 0.5745 + 1.5 + 6.79 1.58479 40.14 0.5845 -6.6 0 1.59551 39.18 0.5772 + 3.3 + 8.2 1.60020 39.67 0.5844 -6.1 +0.5 1.60717 40.29 0.5762 + 3.0 + 7.8 1.61156 40.15 0.5807 -4.2 + 2.0

44.1

3.047

105.9

456 -5.0

+ 1.3

34.9

2.980

110.0

454

-5.5 + 1.5

/ C

Claims (1)

24 claims: 1. Optical Flint glasses with temperature-independent path length in the range from 1.58 to 1.66 _e n, _e ü 44 in to 30, characterized in that they are composed of the following components, in percent by weight: SiO ₂ 6 to 25 B ₂ O ₃ 15 to 36 K ₂ O 13 to 21 BaO .., 6 to 30 ZrO-, 4 to 17 TiO ₂ 6 to 10 Nb ₂ O ₅ 4 to 20 P ₂ O ₅ O to 12 , F 5 to 12